I love tomatoes like crazy, especially homegrown summer tomatoes. This quiche is great then but it is also so good any time of the year. Since you cook the tomatoes down, they become roasted and intensely flavored giving you a hint of those summer beauties. Sometimes I add additional tomato slices to the top as shown but sometimes not. This is also a great recipe to use up tomatoes that are starting to get a little soft.
First, melt butter and sauté onions until soft, about 5 to 7 minutes. Next, add thyme, salt, and tomatoes. Cover and cook on low for 5 minutes. Uncover pan and mash tomatoes. Cook uncovered until mixture is dry and thick. Let cool.
Next, whisk together eggs, milk, and salt. Stir in grated cheese and cooled tomato mixture. Pour into uncooked pie crust.
Bake at 350 degrees for 30 to 50 minutes until knife inserted in center comes out clean.
For a delicious variation, substitute cheddar for the Swiss. Add jalapenos and bell peppers for a Southwest version!